COVID-19 boosters use the same recipe as the original images, despite the emergence of a more contagious delta variant. The vaccines have not been modified to better match the delta because they still work well.
Vaccines work by training your body to recognize and fight the spike protein that covers the coronavirus and helps it enter the cells of the body. Fortunately, Delta’s mutations weren’t different enough to avoid detection.
The increased protection you can get from a booster tuned to better match delta or other options would be marginal, says Dr. Paul Gepfert, director of the Alabama Vaccine Research Clinic at the University of Alabama at Birmingham.
Manufacturing doses with a new formula would also delay the release of boosters.
Moderna and Pfizer are exploring delta-tuned boosters and other options to be ready if ever needed. Health authorities will have to decide if and when it will cost to replace the vaccine formula.
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“What we don’t know,” Goepfert noted, “is that if you have a delta vaccine compared to a regular vaccine, is it really more effective at preventing transmission or asymptomatic infection?”
The US allows booster doses of Pfizer, Moderna and Johnson & Johnson vaccines for certain people, and some other countries also use boosters for those vaccines or other COVID-19 vaccines.